/* atan2 example */
#include <stdio.h>
#include <math.h>

#define PI 3.14159265

int main()
{
  double x, y, result;
  x = -10.0;
  y = 10.0;
  result = atan2(y, x) * 180 / PI;
  printf("The arc tangent for (x=%lf, y=%lf) is %lf degrees\n", x, y, result);
  return 0;
}